Which of the following best describes a key chemical property difference between hydroelectric energy and coal as energy sources?

• A. Both hydroelectric energy and coal rely on oxidation-reduction reactions to generate electricity.
• B. Coal generates electricity by dissolving in water, while hydroelectric energy uses combustion.
• C. Coal undergoes combustion, producing carbon dioxide, while hydroelectric energy does not involve chemical reactions.
• D. Hydroelectric energy releases sulfur dioxide during operation, while coal does not.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the nature of hydroelectric energy and coal as energy sources. Hydroelectric energy is generated by the movement of water turning turbines, which is a physical process, not a chemical one.
2. Step 2: Recognize that coal is a fossil fuel that generates energy through combustion, a chemical reaction where coal reacts with oxygen to produce carbon dioxide (CO\_2), water, and energy.
3. Step 3: Identify that combustion is an oxidation-reduction (redox) reaction involving the transfer of electrons, which results in the chemical transformation of coal into gaseous products.
4. Step 4: Note that hydroelectric energy does not involve chemical reactions like combustion or oxidation; it relies on mechanical energy from flowing water.
5. Step 5: Conclude that the key chemical property difference is that coal undergoes combustion producing CO\_2, while hydroelectric energy does not involve any chemical reactions.